Voice communication quality is generally measured in terms of its reproduction fidelity. If there are gaps or other noise in received communicated voice messages due to a failure to receive portions of voice communications from the talker, the listener will often become distracted and/or agitated, particularly if the listener must repeatedly request the talker to repeat parts of the conversation. Further, the listener may misunderstand the intent of the talker if certain key words are not clearly reproduced at the listener's device. For example, if the talker is requesting that the listener “not” do a described act, such as “do not shoot”, and if the phrase “do not” is not clearly reproduced at the listener's device, and is therefore not heard by the listener, then the listener will misunderstand the intent of the talker.
Push-to-talk (PTT), also known as Press-to-Transmit, is a communication method of having voice conversations using PTT devices that employ on half-duplex communication lines. PTT devices, such as two-way radios, employ a momentary talk button that is activated by the user to switch from voice communications reception mode (where the PTT device user is listening to the voice communications, and wherein the talk button is released) to voice communications transmit mode (where the PTT device user is speaking during the voice communications, and wherein the talk button is depressed or is otherwise activated).
PTT communication systems are often used by government agencies, and in particular emergency service agencies, to provide efficient and secure communications between agency personnel. These PTT communication systems are particularly desirable in situations and/or locations where existing duplex-based cellular communication networks are not available and/or not secure. Exemplary government agencies that provide emergency services include police departments, fire departments, emergency medical services (EMS), or the like, wherein personnel are at a particular activity site performing a service which requires communications to other personnel and/or to an operation station or the like. In some situations, multiple government agencies are providing a coordinated response to an emergency such that the agency personnel from different government agencies are in communication with each other.
There are potential sources of voice communications impairment in a PTT communication system that are small and constant in their effect, such as a loose wire or a defect in the microphone's manufacture. These types of defects may occur in other types of voice communications system.
There also exist highly-variable effects, such as wireless interference or network congestion. Real-time voice communication systems, like full duplex telephone networks, have no recourse for lost portions of voice communications when wireless interference or network congestion occur. In contrast, packet-based communication networks permit retransmission of packets containing voice data that has been delayed, corrupted and/or lost. However, packet retransmission comes at the expense of increased network traffic congestion and/or late delivery of the final voice communications to the listener, which are themselves forms of voice communications impairment. The engineering problem space of using packet-based communication networks for PTT voice communications may be summarized as “correcting voice packet loss of voice communications creates variable delivery timing of the voice communications between the speaker and the listener using PTT type communication devices.” Providing perfect, timely, and error free voice communications for users of PTT communication systems, and particularly for emergency service providers, is essential.
When PTT communication devices suffer from unpredictable time delays, such as time delays that may occur if an intervening packet-based communication network is used to transmit PTT communications from a speaker to a listener, the users (who alternate between being a speaker and a listener) may have a hard time keeping their conversation in step. That is, time delays in the delivery of voice communications data packets over the packet-based communication network may be perceived as “gaps” in the conversation between the users, or may be perceived as periods of silence. A gap of 20 milliseconds or more is perceivable by the listener.
For example, a speaker might ask a simple question, and then listen for the “yes” or “no” reply from the recipient listener. But, if the recipient listener doesn't hear the question for several milliseconds, or even a few seconds, due to packet delays in delivery of one or more voice communications packets over the packet-based communication network, the speaker asking the question might either repeat themselves, or misinterpret the recipient listener's silence as hesitation. The ensuing confusion may last for a few seconds or go on indefinitely in the event of severe packet delays and/or lost packets.
Legacy PTT communication systems are not well configured to operate when an intervening packet-based communication network is used to facilitate communications between the speaker and the listener because of potential deficiencies, such as network congestion, packet loss, and/or frame payload corruption, that may be encountered during the operation of a packet-based communication network. Therefore, emergency service providers who rely of accurate and timely voice communications while using their PTT devices do not rely upon communication systems that employ packet networks, like the Internet, if at all possible.
Accordingly, there is a need in the arts to provide systems and methods that provide users of PTT devices reliable, accurate, and timely voice communications when an intervening packet-based communication network is employed to communicate voice communication packets between the PTT devices.